In UMTS (Universal Mobile Telecommunications System) networks, LTE (Long Term Evolution) has been specified to achieve, e.g., higher data rates and lower delays (non-patent literature 1). To achieve broader bands and higher speeds than LTE, successors to LTE (called, e.g., LTE-A (LTE-Advanced), FRA (Future Radio Access), 5G (5th generation mobile communication systems), and New-RAT (Radio Access Technology)) are also under study.
Existing LTE systems utilize control based on TDD (Time Division Duplex) or FDD (Frequency Division Duplex). In, e.g., TDD, the use of each subframe for either a UL (Uplink) or a DL (Downlink) is strictly defined on the basis of the UL/DL configuration.